Iraq fired a surface-to-air missile at a US aircraft patrolling Kuwait on Saturday, the first time Baghdad has fired outside their own airspace since the 1991 Gulf War, Pentagon officials said.

"We had indications Thursday that Iraq had fired a surface-to-air missile into Kuwaiti airspace," a Pentagon official told AFP.

"Apparently the target was a US aircraft performing a southern watch mission," the official said.

The missile failed to hit the US target, and US patrols were continuing normally, the official added.

The missile was fired in the direction of a Navy E-2 Hawkeye from the aircraft carrier USS Constellation, and went several miles into Kuwaiti airspace, he said.

The United States did not immediately retaliate because of poor visibility and the lack of an electronic signal indicating the origin of the missile, he said.

"There were no electronic fingerprints. Visibility was poor. But our best guess was that it was a surface-to-air missile fired ballistically in the vicinity of the E-2. The missile burst about a mile away" from the aircraft, the official said.

The attack could mark a new tactic by Iraqi forces, who have been trying for more than two and a half years to shoot down US or British aircraft over Iraq, according to the Associated Press.

The United States and Britain patrol no-fly zones over northern and southern Iraq that were imposed after the Gulf War – Albwaba.com